April Luncheon Meeting

ABSTRACT:

Sediment transport and partitioning are important for understanding slope-building processes in mixed carbonate-siliciclastic sediment routing systems. The Bone Spring Formation, Delaware Basin, west Texas is a mixed carbonate-siliciclastic system that has been extensively studied in its basinal extent, but poorly constrained at its proximal, upper slope segment. In this study, we constrain the stratigraphic architecture of the proximal Bone Spring outcrops in Guadalupe Mountains National Park in order to delineate the dynamics of carbonate and siliciclastic sediment delivery to the basin. These upper-slope deposits are composed predominantly of fine-grained carbonate slope facies interbedded at various scales with terrigenous hemipelagic and sediment gravity flow deposits. We identify ten slope-building clinothems that vary from siliciclastic-rich to carbonate-rich; each clinothem is truncated by slope detachment surfaces that record large-scale mass-wasting of the shelf margin. X-ray fluorescence data indicates that slope detachment surfaces contain a higher-than-normal proportion of terrigenous siliciclastic sediment, suggesting failure is triggered by accommodation or sediment supply changes at the shelf margin. Furthermore, a well-exposed siliciclastic-rich clinothem, identified here as the 1st Bone Spring Sand, provides evidence that carbonate and terrigenous sediment were deposited contemporaneously, suggesting both autogenic and allogenic processes influenced the Bone Spring Fm. stratigraphy. This mixing of lithologies at multiple scales and the prevalence of mass-wasting act as a primary control on the stacking patterns of siliciclastic and carbonate lithologies on not only the Bone Spring margin, but also in the distal portion of the Delaware Basin. 

BIOGRAPHY:

Zane Jobe is a research professor at Colorado School of Mines and the Director of the Chevron Center of Research Excellence (CoRE) - http://core.mines.edu/. Prior to Mines, Zane spent 6 years in the Clastics Research Team at Shell Oil Company. His research interests aim to better understand the stratigraphic architecture, scaling relationships, and sediment budgets for clastic depositional systems, with an emphasis on submarine environments. Zane also manages the “Earth Resource Data Science” program at Mines (https://online.mines.edu/er/), which focuses on applied data science and machine-learning using python and subsurface datasets. Zane also enjoys cycling and hunting and thinks that copious amounts of yard work can be cathartic. Zane received a B.S. in Geology from the University of Texas at Arlington in 2004, and a Ph.D. in Geology from Stanford University in 2010 (advisor - Don Lowe).